Icebreaking additional propulsion system and icebreaking ship having the same

ABSTRACT

An icebreaking additional propulsion system includes at least one retractable thruster capable of vertically moving into and out of a hull of a ship. The retractable thruster includes a pair of guide rods vertically installed within the hull, a column vertically movable along the guide rods, a drive unit mounted to an upper end of the column for vertically moving and swiveling the column, and a propeller attached to a lower end of the column for generating propelling power.

TECHNICAL FIELD

The present invention relates to an additional propulsion system for icebreaking ship and, more particularly, an icebreaking additional propulsion system that allows a ship to be moved by means of a primary propeller in case of requiring a reduced propelling power as in a usual voyage but can be operated together with the primary propeller to reduce the load of the primary propeller in case of requiring an increased propelling power as in a voyage across an icy sea of the polar regions.

BACKGROUND ART

As is well-known in the art, a ship specially designed for voyage in the polar regions is called an icebreaking ship or icebreaker. Such an icebreaking ship serves to transport commodities produced in the polar regions to a general living area and services along a voyage route extending over an icy polar sea area and a general non-icy sea area. This means that the icebreaking ship needs to be superior not only in icebreaking speed performance but also in open water speed performance. For this reason, the icebreaking ship requires propelling power greater than that required in a conventional ship.

In view of the voyage in an icy sea area, the icebreaking ship is further provided with a tunnel thruster that assists in an in-port maneuvering. In other words, the icebreaking ship includes separate propelling and steering systems provided independently of each other. This increases the number of devices and makes it necessary to use an electric power with an increased capacity, consequently making the ship costly to build.

Furthermore, the icebreaking ship includes an extra propulsion system in which a propeller is fixed to an appendage of structural body from a hull. In most cases, the structural body is capable of swiveling 360 degrees in a horizontal plane and orienting a water stream generated by the propeller to a desired direction. Therefore, the extra propulsion system configured as above functions as a primary steering device. On the other hand, the extra propulsion system is often provided with an individual housing assembly called a “pod” which is designed into a suitable shape to meet the flowing water. An electric propeller drive motor is arranged in the pod in most cases. This kind of pod-type propulsion system provides a lot of advantages in terms of its function and therefore is applied to a ship in many different shapes. In the pod-type propulsion system, the propeller drive motor is installed within the housing assembly together with a shaft support body and a propeller shaft attached to the end of the shaft support body. The icebreaking ship services an icy sea area in a state that the pod-type propulsion system is mounted to the stern thereof.

However, the pod-type propulsion system is bulky and is mounted to the outside of the ship. For this reason, the excessively great weight and size of a pod unit imposes restrictions on designing the ship. The ship shows reduced performance and suffers from reduction in speed during general voyage. There is also posed a problem in that the initial investment (the price of a ship) grows high and the cost involved in operating a ship becomes high.

DISCLOSURE OF INVENTION Technical Problem

The present invention provides an icebreaking additional propulsion system having a retractable thruster capable of vertically moving into and out of a hull of a ship, wherein the retractable thruster is designed to move down from the bottom of the ship and to serve as an additional propeller during the icy sea area voyage requiring increased propelling power, wherein the retractable thruster allows the ship to come alongside or go away from a pier of a port in a stable manner by astern-going or transverse-going water through a side tunnel and wherein the retractable thruster can be used as a means for dynamic position of the hull to keep the ship in place on the sea.

Further, the present invention provides an icebreaking ship that includes an icebreaking additional propulsion system having a retractable thruster capable of vertically moving into and out of a hull of a ship.

Technical Solution

In one aspect of the present invention, there is provided an icebreaking additional propulsion system including at least one retractable thruster capable of vertically moving into and out of a hull of a ship.

In another aspect of the present invention, there is provided an icebreaking ship including an icebreaking additional propulsion system; and a side tunnel for maneuvering of the ship, wherein the additional propulsion system includes at least one retractable thruster capable of vertically moving into and out of a hull of the ship.

ADVANTAGEOUS EFFECTS

In accordance with the present invention, the retractable thruster is capable of vertically moving into and out of a hull of a ship and swiveling in a horizontal plane. Depending on the voyage conditions, the retractable thruster can serve as an auxiliary propeller. When the ship is isolated in an icy sea area, the retractable thruster performs a retro-propelling function so that the ship can escape from the icy sea area with ease. This helps reduce the load borne by a primary propeller in the icy sea area, thereby making it possible to use a primary propeller having a reduced capacity. During voyage in a general non-icy sea area, the retractable thruster is retracted into the hull of the ship, which helps increase the moving speed of the ship and save the fuel cost. In a port, the retractable thruster allows the ship to come alongside or go away from a pier in a stable manner by astern-going or transverse-going water through a side tunnel.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view showing an icebreaking additional propulsion system in accordance with one embodiment of the present invention;

FIG. 2 is a partially cut-away section view of a hull of a ship, illustrating the icebreaking additional propulsion system in a retracted state;

FIG. 3 is a partially cut-away section view of the hull of the ship, illustrating the icebreaking additional propulsion system in an extended state; and

FIG. 4 is a perspective view showing the icebreaking additional propulsion system on a partially enlarged scale.

MODE FOR THE INVENTION

Referring to FIGS. 1 and 2, the icebreaking additional propulsion system includes a retractable thruster 100 capable of vertically moving into and out of a hull of a ship and swiveling in a horizontal plane. The retractable thruster 100 may be installed in plural numbers in any position of the bottom portion of a hull 10 in a spaced-apart parallel relationship with one another. It is preferred that the retractable thruster 100 be provided in a bow or a stern of the ship. In case the retractable thruster 100 is used in a single number to save an installation space, the retractable thruster 100 is preferably installed in the bow so that it can work well in place of a tunnel thruster.

The retractable thruster 100 includes a pair of guide rods 110 vertically attached to the inside of the hull 10 and a vertical column 112 with a specified length that can move up and down along the guide rods 110. The column 112 is formed of a hollow pipe within which a cylinder rod and a motor shaft may be arranged depending on the kinds of a drive unit 114 described just below.

A drive unit 114 for vertically moving and rotating the column 112 is mounted to an upper end of the column 112. The drive unit 114 includes a motor 114 a for rotating the column 112 and a cylinder 114 b for vertically moving the column 112. A propeller 116 that generates propelling power by rotating is attached to a lower end of the column 112. The propeller 116 is of the type usually employed in a ship and is vertically movable together with the column 112. The propeller 116 is independently rotatable by means of a propeller motor (not shown). A bottom cover 117 is attached to a lower portion of the propeller 116. The bottom cover 117 has a size slightly greater than that of the propeller 116 and has a shape conforming to the lower surface of the hull 10. When the retractable thruster 100 is retracted, the bottom cover 117 becomes flush with the lower surface of the hull 10 and closes off an opening formed on the lower surface of the hull 10.

The icebreaking additional propulsion system of this configuration is operated as follows. During voyage in a general non-icy sea area, the retractable thruster 100 is retracted into the hull 10. This is because the ship can be moved by means of a primary propeller 12 alone (see FIG. 2). When the retractable thruster 100 is in a retracted state, it is possible to eliminate the problems which would otherwise be caused by a conventional pod normally protruding outwardly of the hull. In other words, it is possible to increase the speed of the ship. Furthermore, owing to the fact that the bottom cover 117 remains flush with the lower surface of the hull 10 when the retractable thruster 100 is in the retracted state, it is possible to prevent sea water from flowing into the hull 10 and adversely affecting the voyage speed of the ship.

During the time when the icebreaking ship goes across a polar regions, i.e., an icy sea area, it is required to use an additional propeller. Thus, the retractable thruster 100 is extended downwardly out of the hull 10 as illustrated in FIGS. 3 and 4. More specifically, as the cylinder 114 b of the drive unit 114 comes into operation, the column 112 gets out of the hull 10 and then moves down along the guide rods 110 until the propeller 116 completely protrudes to the outside. The propeller 116 protruding in this manner is swiveled to a desired angular position by means of the motor 114 a together with the column 112, so that the propeller 116 can propel the hull 10 in the same propelling direction as that of the primary propeller 12.

Even when the ship makes voyage across a general non-icy sea area, if additional propelling power is need, the retractable thruster 100 may be extended to generate additional propelling power just like the voyage in the polar regions. In addition, when dynamic position of a ship is performed, namely when keeping the hull 10 in a fixed position on the sea, the retractable thruster 100 is extended downwardly and is operated in a forward or reverse direction by the motor 114 a while swiveling 360 degrees in a horizontal plane against the current of sea, thereby assisting in keeping the hull 10 in a desired position.

The retractable thruster 100 may be used to ensure that the ship comes alongside or goes away from a pier of a port in a stable manner. In this case, the retractable thruster 100 is kept retracted into the hull 10 but is vertically moved along the guide rods 110 so that the propeller 116 can come into alignment with a side tunnel 20 formed in the hull 10. In this state, the propeller 116 is swiveled into a coaxial communicating relationship with the side tunnel 20. If the retractable thruster 100 is operated in a forward or backward direction, the hull 10 is moved to the left or right. For reference, the side tunnel 20 is transversely formed in a submerging portion of the bow or the stern of a container ship to improve low-speed moving performance of the ship, namely to assist the ship in moving toward or away from a pier in a port or turning in a narrow area. With the prior art, a screw propeller is arranged in the center of the side tunnel 20 to generate the propelling power required in moving a ship to the left or right. In the present invention, the retractable thruster 100 is used in place of the conventional screw propeller to assist the ship in moving toward or away from a pier. Furthermore, the retractable thruster 100 assists the ship in turning in a narrow area and improves low-speed moving performance in a port.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims. 

1. An icebreaking additional propulsion system comprising: at least one retractable thruster capable of vertically moving into and out of a hull of a ship.
 2. The icebreaking additional propulsion system of claim 1, wherein the retractable thruster includes: a pair of guide rods vertically installed within the hull; a column vertically movable along the guide rods; a drive unit mounted to an upper end of the column for vertically moving and swiveling the column; and a propeller attached to a lower end of the column for generating propelling power.
 3. The icebreaking additional propulsion system of claim 2, wherein the drive unit includes a motor for swiveling the column and a cylinder for vertically moving the column.
 4. The icebreaking additional propulsion system of claim 2, wherein the retractable thruster further includes a bottom cover attached to a lower surface of the propeller and shaped to conform to a lower surface of the hull so that, when the retractable thruster is retracted, the bottom cover becomes flush with the lower surface of the hull.
 5. An icebreaking ship comprising: an icebreaking additional propulsion system; and a side tunnel for maneuvering of the ship, wherein the extra propulsion system includes at least one retractable thruster capable of vertically moving into and out of a hull of the ship.
 6. The icebreaking ship of claim 5, wherein the retractable thruster includes: a pair of guide rods vertically installed within the hull; a column vertically movable along the guide rods; a drive unit mounted to an upper end of the column for vertically moving and swiveling the column; and a propeller attached to a lower end of the column for generating propelling power.
 7. The icebreaking ship of claim 6, wherein the drive unit includes: a motor for swiveling the column; and a cylinder for vertically moving the column.
 8. The icebreaking ship of claim 6, wherein the retractable thruster further includes a bottom cover attached to a lower surface of the propeller and shaped to conform to a lower surface of the hull so that, when the retractable thruster is retracted, the bottom cover becomes flush with the lower surface of the hull.
 9. The icebreaking ship of claim 6, wherein the retractable thruster is designed to ensure that the propeller comes into alignment with and communicates with the side tunnel when the retractable thruster is in a retracted state for maneuvering of the ship. 